228 CROSSING AND CLOSE-INTERBREEDING. 



The evils entailed upon the aggregate, upon the or- 

 ganization as a whole, and upon the reproductive 

 capacity, constitute the second of the two classes. 



In all organisms, there is, normally, a reciprocal bal- 

 ance of all the organs, and parts, of the respective 

 species. The maintenance of this balance, constitutes 

 full physiological perfection ; and, when any part or 

 parts are wanting, or reduced, this balance is impaired; 

 and an evil effect is wrought, which is over and above 

 the mere deficiency in the parts. The evils, entailed 

 upon the aggregate, are loss of fertility, and of consti- 

 tutional vigor. 



The deficiency, in parts, sometimes works no appre- 

 ciable functional derangement, in such parts, or in the 

 adjoining parts ; although a deficiency, whether work- 

 ing functional derangement or not, in the part, always 

 effects some functional derangement, in the aggregate. 

 But again, quite frequently, the slightest possible loss 

 of tissue, will occasion deleterious effects upon the 

 parts involved, of the most serious character; while, 

 the effect upon the aggregate, or upon the coordinating 

 force of the whole, is infinitesimal, as in blindness. If 

 cousins married, who, in the structure of the eye, were 

 slightly deficient, but not so deficient as to produce, in 

 them, any inconvenience, or consciousness of their de- 

 fect, their offspring would, possibly, then, have said 

 defects augmented, and be wholly, or partially blind. 

 If such couple were proportionately developed in other 

 respects, the evil upon the aggregate, would never be 

 appreciably displayed, in any degree of close-inter- 

 breeding, however long-continued. The degree, in 



